A portable automatic control system for ocean research operation of a ship with a controllable pitch propeller, a rudder and a bow thruster

TECHNISCHE UNIVERNTET Laboratorium voor Scheopshychomodianki

Archlet

Mekehvog 2, 2828 CD Den TOL' OM- 786873 Noe Ma nian

PROCEEDINGS

NINTH

SHIP CONTROL SYSTEMS

SYMPOSIUM

10-14 SEPTEMBER, 1990

BETHESDA, MARYLAND, U.S.A.

VOLUME 2

A Portable Automatic Control System for Ocean Research Operation of a Ship with

a Controllable Pitch Propeller, a Rudder and a Bow Thruster by

HIROYUKI ODA

Akishima Laboratories (Mitsui Zosen) Inc. and

KIYOSHI MASUDA & KEIICHI KARASUNO Hokkaido University, Fisheries

ABSTRACT

The fisheries training ship " Oshoro Maru (1,400 G.T.) " is

equipped with a controllable pitch propeller, a rudder, and a

bow thruster. They are used in combination for both course

keeping and speed control of the ship while

conducting

_{its ocean}

research operation.

While

conducting

_{ocean research operations, manually operating}

the ship via the actuators mentioned above, is _{troublesome due}

to strong external influences such as wind, waves and current.

Adding to the problem is the limited number of _{actuators and so}

on. In order to solve these problems, a portable _automatic

ship control system for ship operation has been _{designed using}

computer simulations and full scale trial at sea.

The Portable Automatic Control System (PACS) _{consists of}

pre-programmed micro computer modules for control, operation, _and

I/O. _{This system makes it possible to directly select several}

combinations

of actuators from

console panels located the

bridge deck and in the research room.

Results obtained so far, indicate _{this control system is able}

to reduce operator _{weariness more than the conventional manual}

cruise operations. _{This paper describes the implemented system}

with particular emphasis on the control system.

1.

Introduction

Fisheries

training

ship " Oshoro Maru " of Hokkaido University

and also fisheries

_{training cruises in the North and South}

Pacific Ocean. [1]

In the case of oceanographic research, CTD equipment and

sounding machine are dropped _{over the ship's side by use of the}

very long cable (more than 3,000m). _{This is done so the crew}

can operate her well at dead slow speeds using the actuators of a Cpp, a rudder, and a bow thruster to keep her course and speed

steady.

_{This prevents measurement equipment from}

_becoming

damage due to cable tanglement under the ship.

However,

manually operating these ship actuators is

_very

troublesome against the external influences such _{as wind, waves} and current. This situation is considerable mental _{and physical} pressure to the operators. _{In order to solve these problems,} we developed a portable automatic controller with particular emphases on keeping the ship's _{course and speed steady in dead} slow speed or under stopping

conditions

_{against the external}

influences. _{The main design consideration is to keep both the}

ship and the instruments safe _{during ocean research operations.}

An approach to achieve this control system and its designing

information

is described in Section 2. The computer simulation

design and mathematical model are summarized in _{Section 3. The}

control system design is reviewed in Section 4. The results of

full scale test and several problems occurred at full scale test

are given in Section 5. Finally, in Section 6 it is concluded

that the ship can be automatically controlled at

smooth and

medium sea

condition,

_{but in rough sea condition, it is}

necessary to adjust the control low and bow thruster for the

endurance problems. It is also concluded that this automatic

control system is safer than skilled manual control

_while

course keeping at dead slow speeds or under stopping

conditions.

2. Design Approach

2.1 _{Oceanographic Operation}

"

Oshoro Maru

" is

specially

designed

for fisheries

training

and oceanographic research. The ship is designed with a stern trawler equipped with a Cpp, a rudder, and a bow

thruster. The particulars of the ship are summarized in Table 1.

An outline of the ship's structure and the photograph are shown

in Fig.1 and Photo.l.

The maneuvering image during

oceanographic observation, which may suggest basic strategies of

the automatic control system, is shown in Fig. 2.

At the

stopping conditions, the long cable deploys the observation

Length(o.a)

LengiNp.p)

Breadth(mId) Depth(m1d)2nd

Upp. Dk Full loaded draft Gross tonnage Japan/Int. Call sign

Main engine Hanshin

Propeller Main generator Dow thrustor Anti rolling tank Trial max. speed

Service speed(15% load)

Number of complement

-Photo. 1 View of "Oshoro Maru"

Table 1 The particulars of "Oshoro Meru"

To prevent the cable from tangling under the ship or into

the screw propeller during the observation, the ship was

controlled as described below:

Get the wind on the port side of the ship about 10 deg. ahead.

Set the ship in

hovering position or with only a small

movement astern.

131 Tuna long line

I I ydraulic line hatalor 0.2t 272m/min. > 1 tel

tit Salmon gill net

llydraulic net hauler 0.3t x I77m/min.

Oceanographic winch Sounding machine

Hydraulic 0.6t x 120m/mm. 4 41 x 5.000m Set

121 C.T.D.winch

Hydraulic It x 72m/min. 6.4 x 4.000m x I set 131 Underwater T.V. winch

Electric 0.5t x 3 12m/min. 20 z 500m X I set

Ill Sampling winch

Hydraulic 2.5t a 120m/min. 12 is x 3.200m X 1 yet

Laboratory

Computer. Disk. Graphic plotter. Printer. Aquarium for culture fishes. Thermu.salinometer.

Fishing .equipment

Soner, Fish finder. Net recorder. Qamitative echo sounding system. Otter trawl dull, logging and analyzing system

Navigation equipment

Gyro compass. Radar x 2. Anti collision system. Hyorid navigation system (LoranA &C.Omega. N.N.S.S.Decca processor). Decca. Electro magnetic log. Ultrasonic anemometer

Fishing gear

Ill Trawl winch

hydraulic lOts 80m/min. 22 # 3000m I set

(21 Net carrier

Hydraulic 0.31 X 100m/min. S 2 sets 72.S5m 66.00m 12.60m 3.40m 5. itint 5.00m 1341301779i it/VA 6EL40 3.2009.s. x 240rprn x 1 set

4 -Waded C.1'.I'. x I set

4501i V A x 3 sets

Thrust5.5t. 390kW x I vet U duct type x 1 set

14.43knots 13.4knots

Officers 139. Crews 27p. Scientists 6p. Cadets 609.

In this manner, if the ship is _{off its desired performance,}

then her course and speed would

_{be adjusted by a Cpp and}

a

rudder. _{However, if this does not produce sufficient results}

then the bow thruster _{can be employed in cooperation with a}

Cpp and a rudder _{without chattering action.}

Fig. 1 An outline of "Oshoro _Meru"

2.2 _{Control Dynamics}

The basic problem for the _{realization of a controller is how}

to obtain practical information useful _{to the object system. One}

of the method is the statistical _{approach which makes use of a}

parametric model that is obtained by

_{the data analysis. The}

design is based _{on the understanding of the system behavior} which is obtained by careful _{statistical analysis of the actual} data. _{By using an appropriate statistical model, this approach}

provides a model that takes into account both characteristics of

the system and noise sources. _{The detail of this method is}

discussed by the authors. [3][4]

Here we introduce the analysis of _{numerical data observed by}

an actual experiment at sea. Fig.3 shows a portion of head

angle, rudder angle and pitch angle of _{thruster. Fig.4 shows}

the decomposition of power of yaw angle, rudder angle, and pitch

angle of bow thruster in relation scale.

_{Fig.5 shows the}

relative power contribution of system variables. These figures

show that the contribution from rudder

_{and bow thruster are}

significant in the low frequency band.

These results _{show the effects of some definite feedback}

relations _{occurring within the controlled variables. These are}

significantly amplifying the frequency

_{components mentioned}

above within the random sea. [5]

MIND.VAVE(11 CURRENT EQUIPMENTS CABLE E.--BOW THRUSTER am. _<4---CPP RUDDER

11111 awn's.

Fig. 3 Observed data ( Actual Sea Test )

TAY

Fig. 4 Power spectrum

m cm em om om om

IA 1

MOM*

0.4M

ON.

Fig. 5 Relative power contribution

2.3 Design Concepts

In aid of the understanding for

the configuration of the

proposed Portable Automatic Control System

(PACS), a brief

description of each concept is given below:

The PACS introduces a step forward control of the shipboard,

by combining the reliability

and flexibility of digital

computers with the simplicity of control procedures.

The manual control of actuators mentioned above, leads to

complex operation adjustment. The PACS may greatly decrease

this troublesome job.

The PACS is able to select the mode of the manual control or

the automatic control for each actuators, and in the automatic

control mode, to select combinations of actuators separately

depending on sea conditions.

The PACS is able to set in suitable position on board, for

example steering room in the bridge deck, wing deck or research

room. Me OM OW"' M CM OM OM OM IOU 11101 TO 100011 0 THROSTIR SM eM 4.0 MUM OM 10100111 OM OM 100010 O. IMO 'TAW

o

The organization of PACS as a whole, is represented _{by Fig.6::}

The PACS can select the control mode of manual _{or automatic in a}

bow thruster, a Cpp and

_{a rudder, respectively as shown in}

Fig.7. The desired direction _{is controlled with a bow thruster',}

and a rudder depending _{on the Cpp movement.}

Also the desired' velocity is controlled with only a Cpp.

3. Portable Automatic Control System

3.1 _{Function and Operating}

INPUT GYROCOMPASS SPEED LOG WIND SENSOR BOW THRUSTER Cpp RUDDER PROCESSOR UNIT OPERATION BOX OUT

Fig. 6 Organization of PACS

Fig. 7 Control mode

We show specific control modes below: * Full Automatic Control

In this case, a bow thruster,

_{a Cpp, and a rudder are}

selected in auto mode. _{A desired velocity and heading}

angle of the ship is set with the dial _{on the operator's panel. A pitch}

angle of the bow thruster, _{Cpp, and rudder angle are calculated}

by the main _{computers in the control console so as to keep her}

velocity and heading angle. _{This is based on the signal}

from the doppler log and gyro compass. The desired direction _are

controlled with a bow thruster and _{a rudder dependent on a Cpp}

movement, and the desired velocity

_{is controlled with only}

a,

Cpp.

* Manual Control

In this case,

_{a bow thruster, a Cpp, and}

_{a rudder are}

selected by manual mode. _{The pitch angle of bow}

thruster and

Cpp are selected in proportion to the inclination _{angle of the}

joystick. The rudder angle is ordered by the indication _{angle of}

the dial.

_{In this mode the}

crew operates the ship with the

joystick lever and the rudder dial.

BOW THRUST( COD RUDDER 0 : POSSIBLE X : IMPOSSIBLE IBOW MUSTER SET UP HEAD x 0 ---x .--0 -.. 0 ... 0 ... 0 0 SPEED x x 0 0 x x 0 0 AUTO. CONTROL THRUSTER X x x X _{0 0 0 0} Cpp x 0 0 X X _{0 0} RUDDER X 0 X 0 X 0 X 0

* Semi-Automatic Control

In this case, a bow

thruster, a Cpp, and a

rudder are

respectively selected by manual or auto mode. For instance,

when a bow thruster is selected in auto mode, and besides a Cpp

and a rudder in manual mode, a desired direction may be set on the operator's panel. Then a pitch angle of bow thruster is

calculated by the computers so as to keep the

direction.

Furthermore, a Cpp and a

rudder may be controlled with a

joystick and dial freely.

The control sequences mentioned above are shown in Fig.8.

Fig. 8 Control sequences

3.2

System Configuration

* Hardware

PACS consists of two components; one is a processor unit with

a 16-bit CPU, and the other is a portable control unit with a

joystick and dial. Photo 2 shows the appearance of the portable

operation box with its joystick, dial and several buttons and

display units.

A single on-board

computer(MAC6000) and the

appearance of the processor

unit are, shown in

Photo.3.

A

special feature is the button switches located on the right side

of the joystick which enables easy mode change.

Once the mode is changed, _{the ship's heading and}

speed can be

controlled by _{selecting the combination mode.}

This can set each actuators on this _{operator's panel in automatic or manual} mode. _{An operator's panel and its faculties are illustrated in}

Fig.9. _{The ship is already equipped with a manual}

operation

apparatus on the operation

_{console in the bridge.}

PACS was

installed

_{by setting the CPU}

_{control circuit}

as shown in

Fig.10, and by using the original control _{apparatus as much as}

possible.

HEAD SETTING SPEED SETTING

DIAL (RUDDER)

Fig. 9 Operation panel

Photo. 3 Processor unit

JOYSTICK(THRUSTER. a Cpp)

WIND INDICATOR

COHPUTER ROOH

I/O BOX PACS

MISR BRIDGE ISWITCH Cpp chit v I I OW THRUSTER RUDDER HYBRID NAVIGATION SYSTEM

Fig. 10 Ship control system

It was judged very important that all in/outgoing signals are

correctly insulated and isolated one from another. For this reason, every input/output signal coming from, or going into,

the PACS is processed according to the scheme of Fig.11. * Software

The implementation of the software design was made bearing in

mind the follows:

an ability to deal with large program size, quick software

analysis, design, writing and debugging, minimizing at faults

during real operation.

possibility to model the software easily

during sea

trials.

For these purposes the application development on the MAC6000

was done in a greatly simplified manner by using high-level

languages and functions. Development aids were prepared and run-time communication support was conducted.

The MAC6000 control program for the PACS is divided into four

parts, and constructed with the following functions: Disposition of extreme values

Filtering of input data

Modified multi variate PID control Wind compensation

Distribution of calculated power to several actuator Management of abnormal movement of several actuator Monitor and printing functions.

The force allocation sequences are as follows:

The total forces and

moment which are required from the

regulators, must be converted to controller, rudder, and Cpp commands. This is done in the force allocation algorithm with and without the use of a bow thruster. The latter mode is used

for the ship operation requiring less vibration

and noise

reduction. In this mode the controller commands to a Cpp and a

rudder are computed to give force and moment balance. The bow

thruster is used for operating at low speed and for hovering.

In this force allocation mode, the controller commands to the

Cpp are not only determined for an axis force, but also for the

rudder turning moment.

If, however, it is not possible to

obtain a sufficient moment, the bow thruster is also controlled

together with the rudder. The commands to the

rudder are

ordered, if the Cpp is going to a positive pitch, even though the corresponding rudder command is always zero

if negative

pitch.

Details of the program structure _{control is presented in} Fig.12. AC 1000 PACT 11100 POOH 0111 PE0ATIO4 DM OPMMIIM .MMCA DIAL .MTCA MM 4111110 NAVIGATIOA SIXTH (railm) 0CORD !MR CM INIAiaANCA) NEADING.CUMALTIME VINO VELOCITV,VIND DIRECTION JOVSTICA.DIAL.SVITCA.SET VALUE.a10. a) DOOR LOAO.UP LOALMITORING

ARDEALRESP0NCES.1IME.A1O. WU( ( SMOONAUSTER.WAUDDER) OUTPUT(TARUSTER,Coo.RUDER)

Fig. 11 Schematic diagram of signal line

4. Simulation Study

4.1 _{Simulation System}

Since the ship _{was not yet built, and the}

control program was

being studied, the _{only practical way to implement the control}

algorithm was to use the simulator technique.

_{For this}

simulation, the main _{hydrodynamic and aerodynamic data were}

obtained from model ship _{basin test and from wind tunnel test.}

The Planner Motion

_{Mechanism (PMM) test,}

which is a kind of

forced oscillation test, was carried out about the scaled model

ship of the "Oshoro

_{Maru" at Akishima}

Laboratories (Mitsui

Zosen) Inc. as shown in Photo.4.

The total simulation was carried out on a desktop

_ship

handling simulator

_{(Called Harbor Master).}

_{The simulator}

communicated with a PACS substitute _{via a serial (RS232C)}

data

link. _{The block diagram of this}

simulator system is shown in

Fig.13. [6] SCALD FILTBRINO PILTSSINO FILTSAINO I TTTTTT CRIIMPUTI AW Cps

Fig. 12 Structure of control program I TTTTTT CO(OUTPUTI MD COMM .04,1 .A10 .I010 ()MUG WIND DIN SOT am. 7 11/11D SENSOR! DATA OVIR 000NAECTOI (0 22222 ION AM DIGITAL ,4011A(CTOI (0 ttttt 10A 801) ,,CONNECTOR 4.1 (MAINTAIIANCE) tttttAR Natritirme) 0' 102326 Tanium. OMM ()ANALOG liO ODA

CONNECTOR0 /0 ANALOGCONNECTOR COMPUTER ROOM

ST COI

VAL. MODS DIAL

&ROYCE

PLUCTU.-ATION

4.2 Ship Dynamics

A mathematical model of three principal equations, describing

longitudinal

and lateral and yaw motion, was developed for the

simulations and the control system design. The variables used

to describe the horizontal ship motions

are explained in

Fig. 14.

The principal equations are expressed as follows: m(u - vr) = XH + XE

m(v + ur) = YH + YE

Izzr =

NH + NE

The hydrodynamic forces

XH, YH,

and moment NH are complicated

functions of ship motion, rudder angle, and propeller thrust.

The external influences

XE, YE,

and NE are complicated

function

of wind, wave, and current forces. [7]

t.r

-COMMAND: BOW THRUSTER

Cpp RUDDER YAW YAW RATE SPEED. INFLUENCE: MIND CURRENT

RESPONCE: BOW THRUSTER

CDP RUDDER SIHURATION DESKTOP SIMULATOR DATA STORAGE DISC

Fig. 13 Block diagram of simulation system

Photo. 4 View of PMM test

Fig. 14 Coordinate system

CONTROL

PACS

OPERATION TERMINAL

4.3 _Simulation

Results

Before implementing _{the PACS to an actual ship,}

we tried a

control simulation. _{The main purpose of these}

simulations were

to examine the control _{algorithm and}

gain constants for the PACS.

Fig.15 and Fig.16 show the

_{course and velocity}

stability

performances of the _{PACS in terms}

of _{trajectory, time history}

of heading,

_{velocity and}

several actuators.

_{Through these}

control simulations,

the control algorithm and _{gain constants}

were reasonably

_planned.

The circumstances

_{during the}

simulations are shown in Table _2.

5. Full Scale Test

5.1 _{Test's Results}

The PACS is

_{currently operating}

the "Oshoro Maru". _{It is}

installed as a part of an

integrated system. _{Fig.17 shows}

the result of the PACS operating _{the ship in}

light sea condition.

These were carried out

under relative condition wind speed

averagely 10 (m/s) _and

the direction _{of about port 10 (deg.)}

bow.

_{This figure}

shows the

_{ship's velocity}

and course

deviation. _{We can see that}

velocity and course keeping _quality

is stabilizing.

Fig.18 shows _{typical result}

from the sea tests in a fresh

breeze state.

This test was carried out

_{under the wind}

condition of _{relative speed}

until speed 10 _{(m/s) averagely and}

the direction of port 10 _{(deg.) bow}

was obtained. These were

wide fluctuation in direction. _{In this}

case, the course keeping

performance was becoming _wrong.

These results _{suggest that if}

fluctuations of wind direction

are wide, the control sequence of the bow

thruster can't satisfy

the course keeping _performance.

Table 2 Circumstance of simulation

HEAD(deg) SPEED(k1.8) vol. _{dir.(deg) vel.(las)}

I dir.(deg)

0.0 0.0 10.0 _{350.0 0.0}

0.0

350.0 0.5 10.0 340.0 1.0 I 170.0

DES 1RED _INFLUENCE

VALUE

current

.wind

1130 134c1 309 540

YAW

5.2 Problems

The full scale tests carried out on PACS, indicate that a PID controller would be very difficult to implement with sufficient security over the entire range of operations for the "Oshoro Maru".

41.50 .0.13 Wm

02.W

Fig. 15 Simulation result (under wind & current)

.00 Ikts1 Vx 0 wind

\I

1011 (sic) y (Ye

Fig. 16 Simulation result (under wind) YAW ft, .0.11 am. -0.05 Mifl. -0.1? 3.0 eve. 4.97 min. .0.03 1 Vy 4 4 Wn. 4 e I ) Vy . m, ,ti Wm 4 0 l BOW THRUSTER ...j -N ..:.:,

i'l lr m

1490/ MIL 4.01 -0.80 -10.33 P' BOW THRUSTER

vim

11.11 M sad 00 7:.11 CP P . -3.03 iv* 1.32 min. 4.113 10(01 RUDDER 4.70 win. -24.62 IRO Lmr.1 5.10 720 Ideol RUDDER .3.17 -0.11 Wm -35.W 110 10931 31313 510 733 0 M WO 30 540 WO 1 tee 2.45 *0.01 140 7:0 0.12 lcu.minuu. I. 11 15tC2 0.13 x 0.211111LE/. 1.. 0 - 720 15E0

0 Ws, .10 .0? .W .10 03 .03

The reason for this lie in several

_{characteristics}

as

described below:

* It is clear

that the pressure system of the _{bow thruster}

of "Oshoro Maru"

_{is not}

preliminary designed

_{for continuous}

driving.

* Conventional PID control _{predominantly deals}

with linear

systems within moderate disturbances.

However,

_{this control}

_approach

will not always

_be

satisfactory when

_{the operating}

conditions change.

_The

actuators of a bow thruster,

_{a Cpp and a rudder}

have the

requests of the

_{operation with a nonlinear}

characteristics.

These create

difficulties unless special precautions _{are taken.}

284 (deg) 254 224 2 (kts) -2. 20 (deg) 0 -20 40 -40 TAN ANGLE SPEED RUDDER 284 (deg) 254 224 2 (kts) 0 -2 20 (deg) 0 -20 YAP ANGLE SPEED BOP THRUSTER coo 40 RUDDER

77-6iztv

(deg) 0 (deg) 0 (sec) 600 (sc)

Fig. 17

_{Full scale result( light sea )}

_{Fig. 18}

_{Full scale result(breeze sea)}

(set course & speed 255 deg., 0.5 kts)

_{(set course & speed 255 deg., 1.0 kts)}

6. Conclusions

The PACS for oceanographic maneuvering of the "Oshoro Maru" was designed. The performance of the PACS was investigated by

simulating studies and actual sea tests.

The PACS has the

following features:

The PACS can operate the ship and the actuators under

manual, semi-auto, and full automatic control by mean of

actuator selection buttons.

The PACS can control the ship's heading and speed

automatically in the automatic mode.

Joystick and dial control can adjust the ship's velocity and direction.

The PACS is operated away from the control console.

The PACS has high reliability with the adoption of a board

computer and a ROM in the processor unit.

Based on the owner's specification of the ship, as well as

the condition of the sea in the area where the vessel is to

operate, the control situation is

simulated to help in the

design and operation of the PACS.

It is concluded that the ship can be automatically operated at

wind speeds not exceeding approximate 10 (m/s) and when wind

direction is almost steady.

For wide fluctuations of wind

direction, it is necessary to modified the control sequence in consideration of the pressure system of bow thruster. Now we

are going to describe simple robust methods that can be used to

get crude estimates of automatic control system.

7. Acknowledgments

The authors are grateful to the crew of the "Oshoro Maru" for their help in implementing the PACS and their support in the

actual sea tests.

References

[1] "Data Record of Oceanographic Observations and Exploratory

Fishing", No.33, The Faculty of Fisheries, Hokkaido University, March, 1990.

H.Oda, K.Masuda and K.Karasuno, "Development _{of Portable} Automatic System for the Fisheries Training Ship", 29th SICE

'90, Tokyo, 1990. (in Japanese)

K.Ohtsu, M.Horigome, Y.Yamanouchi, _{M.Hirano and H.Oda,}

"Development of Energy Saving Auto-Pilot

_System

_through

Statistical Optimal Control", Mitsui Technical Review, Vo1.120, 1983. (in Japanese)

H.Oda, "Identification of Feed Back System through

Parametric Model", Report of UJNR-MEC

_{Panel, 12th Joint}

Meeting, Maryland, 1983.

H.Oda, K.Masuda, K.Karasuno, K.Ohtsu

_{and S.Januma,}

"Design of Course Keeping System at the Dead Slow Speed Applying the Multiple Auto-Regressive Model", 14th SICE System Symposium, 1988.(in Japanese)

S.Moriya and M.Hirano, "Development of a Desktop Simulator

and its Application of Simulator

_{Link", MARSIM & ICSM 90,}

Tokyo, 1990.

K.Karasuno, K.Yoneta, S.Januma, "A New Mathematical Method

of Hydrodynamic Force and _{Moment Acting on Hull in Maneuvering}

Motion at Slow Speed and Oblique Direction", Journal of The

Kansai Society of Naval Architects,

_{No.209, June, 1980.(in}